Immunotherapy for melanoma
Melanoma is the most aggressive skin cancer and one of the most aggressive cancers that can affect humans, and the reason behind that is its early spread. Unlike squamous cell carcinoma of the skin, melanoma can spread to the blood or lymphatics early making its surgical treatment impossible. Fortunately, if there is a cancer in which the role of immunotherapy shines, it has to be melanoma. Ever since immunotherapy was used for this malignancy, the survival of cases with stage III melanoma improved dramatically.
The main type of immunotherapy used in melanoma are checkpoint inhibitors, and they work by activating T-cells of the blood and letting them attack the cancer cells. Three main checkpoint inhibitors are available for cases of surgically unresectable melanoma: Ipilimumab, Pembrolizumab and Nivolumab. Pembrolizumab and Nivolumab act on a specific receptor on T-lymphocytes called PD-1, and when they bind to it, the inhibition of T-lymphocytes is removed, and they are allowed to attack cancer cells at will. They can be used alone or a combination of the two drugs Ipilimumab and Nivolumab may be used for better results. They can also be used in select resectable cases after surgery (neoadjuvant therapy). The reason as to why the combination of the two drugs is not a standard regimen is that it comes with more severe side effects and a higher risk of developing an autoimmune reaction.
Interleukin 2 is one of the key cytokines secreted by white blood cells in response to viral infections and cancer. It is produced as a medicine and can be given as an intravenous infusion in some cases of advanced melanoma where it stimulates the immune system to attack cancer cells, but it has mostly fallen out of favor and replaced by immune checkpoint inhibitors owing to its higher risk of inflammatory side effects.
Local injection has been in use for a while in treating advanced melanoma. It relies on inducing an immune reaction that destroys cancer cells locally. Among the options is the BCG injection into the melanoma. BCG is the tuberculosis vaccine which can stimulate an immune reaction locally to destroy cancer cells. Another example is the T-VEC therapy which is the local injection of a virus into the melanoma cells to kill them. The virus commonly injected is herpes simplex.
Advanced melanoma with multiple distant metastases still has a bad outcome and a high risk of mortality despite advances in immunotherapy. New clinical trials are needed to develop new drugs or test the effectiveness of existing ones for advanced cases of melanoma.